U.S. Pat. No. 5,578,058 (the prior art) issued to the same inventor of this application disclosed a hygienic pacifier having a bivalve shell hingedly secured to the base member for closing the nipple portion protruding from the base member for preventing contamination of the nipple portion.
However, such a prior art still has the following drawbacks:    1. When the two half-shell pieces (31) are opened for baby's soothing, the two half-shell pieces (31) will be obstructed beyond the baby's mouth, being unable to be swallowed by the baby. However, when the bivalve shall (3) is closed, the pacifier may be possibly swallowed by a baby to possibly cause baby's fatal suffocation.    2. It is lacking of automatic closing mechanism for closing the bivalve shell (3). Even a pair of meshed gears 34a are provided for simultaneously closing the two half-shell pieces (31), at least one half-shell piece (31) should be continuously driven for closing the two half-shell pieces, still being inconvenient for closing the bivalve shell for protecting the nipple portion.
The present inventor has found the drawbacks of the prior art and invented the present anti-swallow pacifier.